Process for finishing a wooden board and wooden board produced by the process

ABSTRACT

A process for finishing a wood or wooden board, in particular an MDF or HDF board, with an upper side and an underside. The process includes applying a sealing layer of melamine resin to the upper side of the board and printing a decoration onto the sealing layer. A protective layer is applied of melamine resin to the decoration and the board is pressed under the action of temperature until the protective layer and the sealing layer melt and bond to each other with the inclusion of the decoration printed on.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The invention generally relates to a wooden board and a processfor finishing a wooden board, in particular an MDF or HDF board with anupper side and an underside. These boards may be used, for example, forfurniture construction and panels, in particular flooring panels.

[0003] 2. Background Description

[0004] Flooring panels with a substrate board made of wood are normallydesignated laminate panels and have been on the market for many years tosubstitute for parquet. The desired decoration (parquet, wood grain,tiles, and so on) is printed onto a paper web, which is subsequentlycoated with resin and rolled up on a roll or stacked as sheet goods. Thedecorative web prefabricated in this way is laid on the substrate boardat the flooring manufacturer and is pressed.

[0005] As a result of printing the decoration onto the paper web, thelater sealing of the paper web with synthetic resin and the subsequentconnection of the decorative layer to the substrate board by means ofpressure and temperature, the dimensions of the paper web are changed.Those skilled in the commonly refer to this phenomenon as paper growing.The paper grows both in length (lengthwise growth) and also in width(widthwise growth).

[0006] If this decorative board is then to be cut to size to formindividual panels, the lengthwise and widthwise growth must be takeninto account, since otherwise there would be an unequal distribution ofthe decoration on the individual panels. This would result in the floorassembled from an unequally distributed decorative layer havingundulations in the decoration at the connecting edges of the panels.Even if such undulations in the decoration are only a few millimeters,they are striking when viewed, which has a detrimental influence on theesthetic impression and therefore reduces the quality of the laid floor.

[0007] In order to be able to produce in suitable quality, the papergrowth must be registered and the saw which saws the panels out of thesubstrate board must be adjusted appropriately. Manual adjustment isvery time-consuming. DE 100 19 054 C1 describes a method of cuttingpanels to size from a substrate board with which the saw can be matchedautomatically to the paper growth. For this purpose, cameras are neededwhich determine the actual position of defined decorative points. Theactual position is then compared with the intended position and thedeviation of the width or length dimension is determined, so that thesaw can be adjusted appropriately.

[0008] In order to optimize the cutting, it is therefore necessary toexpend a great deal of effort, which makes the production ofhigh-quality panels expensive. In order further to match the visualquality of the laminate panel to the visual quality of a natural woodpanel, in the press in which the decorative layer is pressed with thesubstrate board, a die plate having a relief can be provided, whichimpresses a relief corresponding to the wood grain into the syntheticresin layer. Since the paper growth is not reproducible, it is notpossible to bring the relief completely into coincidence with thedecoration. The joints of a tiled surface cannot be impressed into thesurface, since deviations here would immediately be visible.

[0009] Starting from this problem, a process for finishing a woodenboard is to be specified with which the disadvantages described aboveare avoided.

SUMMARY OF THE INVENTION

[0010] The problem is solved with a wooden board by means of thefollowing steps:

[0011] a) applying a sealing layer of melamine resin to the upper sideof the board,

[0012] b) printing a decoration onto the sealing layer,

[0013] c) applying a protective layer of melamine resin to thedecoration, and

[0014] d) pressing the board under the action of temperature until theprotective layer and the sealing layer melt and bond to each other withthe inclusion of the decoration printed on.

[0015] The board is preferably further finished by means of thefollowing steps:

[0016] e) applying a sealing layer of melamine resin to the underside ofthe board,

[0017] f) applying a colored layer to the sealing layer,

[0018] g) applying a protective layer of melamine resin to the coloredlayer,

[0019] h) pressing the board under the action of temperature until theprotective layer and the sealing layer melt and bond to each other withthe inclusion of the colored layer.

[0020] In another aspect of the invention, a wooden board, in particularflooring panel, comprises an HDF or MDF substrate board with an upperside and an underside. The upper side has a decoration, wherein asealing layer onto which a decoration is printed is applied to thesubstrate board. The decoration is covered by at least onewear-resistant layer.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021]FIG. 1 shows a flow chart of the method of finishing a board inaccordance with the invention; and

[0022]FIG. 2 shows a cross sectional view of an embodiment of the boardin accordance with the invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0023] Referring to FIG. 1, a flow chart of the method of finishing aboard in accordance with the invention is shown. It should be understoodthat FIG. 1 is representative of the steps of the finishing process;however, FIG. 2 may equally represent some of the finishing processes aswell as the resultant board or panel using the process of the invention.For example, the flow of FIG. 1 shows:

[0024] a) applying a sealing layer of melamine resin to the upper sideof the board,

[0025] b) printing a decoration onto the sealing layer,

[0026] c) applying a protective layer of melamine resin to thedecoration, and

[0027] d) pressing the board under the action of temperature until theprotective layer and the sealing layer melt and bond to each other withthe inclusion of the decoration printed thereon.

[0028] The fact that the decoration is printed onto the board means thatnot only are the problems associated with the paper growth avoided butalso the handling associated with laying the paper web on the upper sideof the board. As a result of applying the sealing layer to the substrateboard, the printing ink is prevented from being absorbed by thesubstrate board, which would be the case without the sealing layer,since the substrate board as such is absorbent.

[0029] By means of the sealing layer, the decorative color is kept onthe surface and bonded, so that the decorative layer remains on thesurface and forms a precise, clearly visible decoration. The protectivelayer of melamine resin replaces the known overlay which, in the knownfinishing processes, is laid on the decorative paper. By means of thesubsequent pressing under the action of temperature until the protectivelayer and the sealing layer melt, the decoration is enclosed and thesealing layer and protective layer become a composite. With the aid ofthe press plate, the level of gloss of the surface can be adjusted. If apolished press plate is used, a highly glossy surface is achieved.

[0030] The board is preferably further finished by means of thefollowing steps, as represented in FIG. 1, for example.

[0031] (i) applying a sealing layer of melamine resin to the undersideof the board, and

[0032] (ii) applying a colored layer to the sealing layer.

[0033] The protective layer of melamine resin may be applied to thecolored layer, and the board may be pressed under the action oftemperature until the protective layer and the sealing layer melt andbond to each other with the inclusion of the colored layer.

[0034] By means of these steps, the otherwise usual undercoat in thecase of a laminate panel is replaced. The individual layer thicknessescorrespond to those on the upper side, so that distortion of the boardis ruled out. It is particularly advantageous if the upper side and theunderside are finished at the same time, which reduces the productiontime.

[0035] The finishing of the board can be carried out continuously, acontinuous press preferably being used for the pressing. In this way,the production time is shortened further, which reduces the productioncosts.

[0036] The sealing layers 102 and/or the protective layers 104 arepreferably applied in a plurality of individual layers, each individuallayer drying out before the application of the next layer. Theindividual layers have a weight per unit area of 10-40 g/m² in eachcase. The sealing layer 102 preferably includes two individual layers;the protective layer of four individual layers. In addition, theprinting ink 106 can be applied in a plurality of layers.

[0037] In order that the decoration or the colored layer 106 does notmelt or experience a color change during pressing, an appropriatelyheat-resistant color or heat-resistant varnish 107 can be applied inaccordance with the invention. The varnish layer may be electron-beamcured or UV cured.

[0038] In order to obtain a smooth surface, the board 100 is preferablyground 108 before the first individual layer of the sealing layer isapplied. Corundum 110 may be mixed into or scattered into at least oneindividual layer of the protective layer 104 in order to increase theabrasion resistance. Antibacterial and/or antistatic additives 112 canalso be mixed into or scattered onto the protective layer 104. This canbe carried out in the same or in another individual layer. All theindividual layers are preferably treated correspondingly.

[0039] Fillers 116 can be introduced into the sealing layer 102 and/orthe protective layer 104. Suitable fillers 116 are wood fibers, wooddust, metals, mineral substances (clay, sand), plastics, cellulose orash. The fillers 116 can achieve a structure, which is applied so as tocorrespond with the decoration, so that fine reliefs can be produced. Inthe individual layers on the underside, the fillers are used, forexample, for damping the sound of footfalls.

[0040] The finishing of the upper side of the board can also be carriedout only in some regions. The finishing is preferably carried out on anarea of the board running obliquely with respect to the upper side. Forthis purpose, a number of V joints 118 can be embossed into the upperside of the board. Following finishing, the board is sawed up centrallyalong the V joints, so that individual panels whose side edges have achamfer are produced. These chamfers subsequently underline the visualimpression of a joint between individual panels of a floor.

[0041] Since no paper layers are used, the boards are safe againstdistortion which could arise as a result of the inherent tensile forceof the papers. Because of the thin layers, short process times can beimplemented. The fillers introduced into the individual layers on theunderside of the board can be provided in order to dampen the sound offoot steps, for example.

[0042] Instead of finishing a substrate board of high or medium densityfibreboard (HDF or MDF), oriented strand board (OSB boards) orconventional chipboards with a correspondingly finely distributed toplayer can also be used. It is also conceivable to form the sealing layerso thickly that irregularities in the board (OSB) are compensated for.The boards can be used not only as flooring panels but can also be usedin furniture construction.

[0043] Parts of the process according to the invention are suitable toimpart laminate properties to a board with a real wood surface (woodensubstrate board with veneer layer, solid wood), specifically highabrasion resistance, high impact resistance and an adjustable level ofgloss. For this purpose, it is possible to dispense with the applicationof the decorative layer to the upper side or the colored layer to theunderside. The subsequent sealing of the laid parquet can therefore bedispensed with. By printing on an appropriate decorative layer,inexpensive timbers can be increased in value. For example, an oakdecoration can be printed onto a pine veneer and its color emphasizedappropriately.

[0044] The press plate can be provided with a relief corresponding tothe decoration, when the board is pressed, depressions are then producedin the protective layer, which for example correspond to a wood grain orto a tiled surface. The touch of the surface is then matched to anatural surface.

[0045] In particular, V joints running in the longitudinal directionand/or transverse direction of the board can be impressed into theprotective layer. During the further processing, panels are then sawedfrom the board by sawing being carried out centrally along the V joints.As a result, the panels are then given a chamfered edge. These featuresare shown in FIG. 2, which can equally represent the process offinishing the boards.

[0046] While the invention has been described in terms of embodiments,those skilled in the art will recognize that the invention can bepracticed with modification within the spirit and scope of the appendedclaims.

1. Process for finishing a wood or wooden board, in particular an MDF orHDF board with an upper side and an underside, comprising the followingsteps: a) applying a sealing layer of melamine resin to the upper sideof the board, b) printing a decoration onto the sealing layer, c)applying a protective layer of melamine resin to the decoration, and d)pressing the board under the action of temperature until the protectivelayer and the sealing layer melt and bend to each other with theinclusion of the decoration printed thereon.
 2. The process as claimedin claim 1, further comprising the following steps: applying a sealinglayer of melamine resin to the underside of the board, applying acolored layer to the sealing layer on the upper side of the board,applying the protective layer of melamine resin to the decoration, andpressing the board under the action of temperature until the protectivelayer and the sealing layer melt and bond to each other with theinclusion of the colored layer.
 3. The process according to claim 1,wherein the upper side and the underside are finished at the same time.4. The process according to claim 1, wherein a plurality of individuallayers are applied for at least one of the sealing layer and theprotective layer and each individual layer dries out before theapplication of the next.
 5. The process according to claim 2, whereinthe board is ground before the sealing layer is applied.
 6. The processaccording to claim 4, further comprising providing corundum into atleast one individual layer of the protective layer.
 7. The processaccording to claim 4, further comprising scattering corundum onto atleast one individual layer of the protective layer.
 8. The processaccording to claim 4, further comprising mixing at least one ofantibacterial and antistatic additives into at least one individuallayer of the protective layer.
 9. The process according to claim 4,further comprising scattering at least one of antibacterial andantistatic additives onto at least one individual layer of theprotective layer.
 10. The process according to claim 1, furthercomprising providing at least one filler into at least one of a sealinglayer and the protective layer.
 11. The process according to claim 10,wherein the filler is wood fibers, wood dust, metals, mineralsubstances, plastics or ash.
 12. The process according to claim 1,wherein finishing of the upper side of the board is carried out only insome regions.
 13. The process according to claim 10, wherein finishingis carried out on an area running obliquely with respect to the upperside.
 14. The process according to claim 1, wherein a structure or atleast one V joint is impressed into the protective layer.
 15. A woodenboard comprising an HDF (high density fibreboard) or MDF (medium densityfibreboard) substrate board with an upper side and an underside, theupper side having a decoration, wherein a sealing layer onto which adecoration is printed is applied to the substrate board, and in that thedecoration is covered by at least one wear-resistant layer.
 16. Thewooden board according to claim 15, wherein the sealing layer is formedof melamine or urea resin.
 17. The wooden board according to claim 15,wherein the decoration is printed directly onto the sealing layer. 18.The wooden board according to claim 15, wherein the decoration comprisesheat-resistant colors.
 19. The wooden board according to claim 15,wherein the wear-resistant layer is a varnish layer.
 20. The woodenboard according to claim 19, wherein the varnish layer is electron-beamcured or UV cured.
 21. The wooden board according to claim 15, furthercomprising structuring means or corundum granules applied to thedecoration in order to increase the abrasion resistance.
 22. The woodenboard according to claim 19, further comprising structuring means orcorundum granules embedded in the varnish layer.
 23. The wooden boardaccording to claim 15, wherein the substrate board is smooth on at leastone of the upper side and underside.
 24. The wooden board according toclaim 15, wherein the substrate board is ground on at least one of theupper side and underside.
 25. The wooden board according to claim 15,further comprising a structure or at least one V joint embossed into thewear-resistant layer.